Temporary Bulk Change / Anime & Manga

• Ai Kora:
  • In chapter 59, Ayame overeats (over the course of a couple of weeks) due to stress from a scandal at her father's company and becomes rather obese. When she hears that the scandal was cleared and the company's stock had gone back up, she reverts back to her slim figure instantly. Meanwhile, Hachibei had been intercepting all of Ayame's food during the day and grew as bloated as Ayame had been in just a day. At the end of the chapter he throws all of it back up, and by the next chapter he's back to normal.
  • In chapter 88, this happens to some of the girls in Hachibei's dorm after Gokou Ooba, a chubby-chasing rich boy who fell for the fattened-up version of Ayame, slips a "bountiful body drug" into the dorm's water supply. The chapter ends with each member of Gokou's Maid Corps taking a dose of the drug, confessing their collective love for him, and inflicting severe bruises on their beloved master when the plumped-up maids all try to hug him at once.
    Maeda: Liking fat can be a problem...
• Buccha from Air Gear can do this as it's explained that most of the fat is in fact blood pooling in his stomach from overeating. When he wishes, he can transfer it to his muscles to give himself a more impressive build.
• This clip from Assemble Insert has a woman gaining muscle mass when strenuously trying to bend a lead pipe. When the deed is done, she immediately returns to a more slender shape.
• Araki Ryuuichi from Area no Kishi lives through this trope. When we first see him, he almost looks obese and complete different from when he used to be the midfielder of the FC. By a couple of episodes, he returns to his slim handsome body within 10 days. By episode 8, however, he lets himself go again and his weight becomes a recurring joke, with comical moments towards his bulging gut and how out of shape he is.
• Bleach:
  • Kirio Hikifune is shown to be one of the fattest characters in the series. It turns out, she actually fattens herself up because her special technique drains most of her spirit energy, slimming her back down. So she basically has to be fat to survive her technique.
  • Meninas McMallon has the ability to drastically increase the size of her muscles.
• At the end of the tenth episode of Brave Beats, ten-year old Hibiki is made outrageously muscular after Santa misinterpreted his wish to become stronger. Upon realizing what happened, the poor kid immediately starts running after Santa to change him back, but he's back to normal by the next episode.
• Kaseki from Dr. STONE temporarily becomes massively muscular whenever he gets excited about engineering. This is an actual physical transformation, and not just a visual gag, as shown when he escaped from being tied up by hearing how modern tractors work and breaks the ropes, which were measured for his smaller, normal body.
• Dragon Ball:
  • Master Roshi. He can increase his muscle mass from normal old man muscles to bodybuilder muscles within seconds, and lose it even quicker. He wasn't the only one who did things like this, but his was the most extreme.
  • Zarbon has been known to change from a skinny Bishounen to a fat, muscular, lizard monster when he fights. It should be noted that the latter form is actually his real one, but he despises its ugliness.
  • Frieza, once he's forced to draw out all his power in order to even have a chance against Super Saiyan Goku, bulks up considerably as he goes from skinny to even beefier than Goku.
  • During the Cell Saga, the Saiyan characters discover a "half-level" of Super Saiyan^note Officially called "Super Saiyan Grade 2" or "Grade 3" that pumps up their muscles greatly; however, only the inexperienced Trunks seriously uses it, since the more savvy Goku and Vegeta realized that it slows you down too much to be really useful.
    • Movie-exclusive villain Broly is famous for this, having his own personal level of Super Saiyan (dubbed "Legendary Super Saiyan") which makes him almost double in size and become incredibly beefy but without suffering any of the drawbacks seen with SSJ Grades 2 and 3.
  • Kale, a female Universe 6 Saiyan from Dragon Ball Super, is able to temporarily transform from a meek, skinny girl into a tall, beefy powerhouse through her Super Saiyan Berserk transformation.
• Secondary character Lislie of the Mermaid Heel guild from Fairy Tail appears to be fat, but she can use her gravity-modifying magic which causes her to turn into a slim, more attractive girl.
• Futari Escape: In chapter 19, after blowing money on food-making toys in the last chapter, Kouhai gains a massive amount of weight just two weeks before her manga publisher's awards party. Senpai convinces her to work out to burn the weight off in time, and she succeeds ... only to end up exceptionally ripped.
• In The Hero Who Returned Remains the Strongest in the Modern World, Daiki's Enhance Physical Ability skill multiplies his Super-Strength several times over, with the side effect of increasing the size of his muscles to the point that his school uniform is forcibly unbuttoned and the sleeves are stretched taut against his biceps and shoulders.
• The title character of High School Ninja Girl, Otonashi-san puts on a lot of weight over the holiday break. She struggles between trying to lose the weight and giving in to her Big Eater nature. Getting flustered over her feelings for male lead Arima causes her to sweat the pounds away literally overnight.
• The titular Mizore from Melt Away! Mizore-chan is a snow woman who can replenish herself by eating cold foods if she starts to melt. If she overeats then she becomes incredibly fat and can stay in the summer sun for extensive amounts of time before she melts back down to her original size.
• My Hero Academia
  • All Might suffered a near Career-Ending Injury that prevents him from using his full strength and original Heroic Build body for long. When not actively using the power of One For All, he is an emaciated skeleton of a man. He directly compares his situation to a guy puffing up his chest to look buff.
  • Fat Gum is normally a big guy whose quirk gives him lots of fat that absorbs impacts. In a pinch, he can burn the fat to augment his strength and endurance and he looks like a much smaller but still buff guy until he loads up on more food.
• Naqua-Den: At one point Big Eater Taro wins a rice-eating competition against a gluttonous youkai, however the amount of food ingested is enough to break his super-metabolism and the following day he wakes up fat. Hopefully his next supernatural battle involves a sumo match, which his newly found weight qualifies him for. He later quickly returns to his normal size.
• This ability is the special technique of the Akimichi Clan in Naruto. They can change the size of their bodies by converting calories into chakra. They can choose to expand only parts of their bodies, like their fists, or turn themselves into giants. This justifies the heavy-set build of Choji and his father; without a high calorie diet, they wouldn't be able to use as much chakra.
• In Nerima Daikon Brothers, Ichiro, Pandaikon, and Hideki grow muscles thanks to Kimchi during episode 2.
• In One Piece, Luffy is able to temporarily increase the size of some of his body parts when he goes into Gear Third. He then shrinks when the effect subsides. He also overeats in several episodes and inflates. Sometimes it lasts somewhat long.
• One episode of Panty & Stocking with Garterbelt sees Stocking gain a little weight due to her sweet tooth. She brushes it off and starts exercising heavily, but not only does this not work she wakes up to find herself with a Balloon Belly. Stocking freaks out and chows down on sweets, causing her to grow until she is the size and shape of a parade float. Once she and Panty kill the ghost responsible for this, Stocking returns to her normal size.
• In episode 4 of Sabagebu!, Momoka's weight fluctuates wildly as she struggles with her snacking habits.
• When Fuu on Samurai Champloo eats a great deal of food, she temporarily swells to a massive size. In at least one episode, this renders her unrecognizable to a set of police officers when she slims back down afterward. ("Have you seen a girl around here? She was really fat.")
• In the first episode of Tamagotchi, Kuchipatchi eats too many burgers at the race's burger stand and becomes rounder in shape than usual, causing him to bounce all around Tamagotchi Town when he accidentally trips. Right as Mametchi saves him from a rough fall, he returns to his original shape.
• In Toriko, this is the result of eating the Meteor Garlic. This gave the food its other name, the Doping Garlic. For an example of its effect, it took Komatsu from this◊ to this◊.
• At the start of episode six of Wandaba Style, Susumu is in the middle of a slump, and without one of his experiments to liven things up, the girls have nothing to do and have gained a substantial amount of weight as a result. When they realize just how fat they've gotten, they're quick to lose most of the extra pounds.